Aluminium pigments have been commonly used in automotive metallic finish, in decoration finish of plastics, in printing inks and the like. When coloring is desired, color pigments were used together with aluminium pigments. In such cases, it was a problem that a vivid color tone was difficult to obtain by the fact that achromatic tone inherent in aluminium pigment was emphasized. Flake pigments consisting of colored inorganic flaky materials such as mica flake have been also used in place of aluminium pigments. Such flake pigments could give a pearly color tone of their own, but had drawbacks including a small hinding power and a poor metallic luster.
Similar problems arose when aluminium pigments were incorporated into resins to obtain a better decoration effect.
In order to solve the problems as set forth above, several processes have been proposed to obtain a colored aluminium pigment by depositing a color pigment onto the surface of an aluminium pigment with the aid of polymer coating technique (e.g., JP-A-58/141248 and 05/508424, JP-B-94/92546, etc.,). These proposed processes, however, have failed to give a vivid color tone because of the difficulty in depositing a sufficient amount of color pigment on the surface of aluminium pigment. Even though a process succeeded in depositing a sufficient amount of color pigment, other problems such as an easy exfoliation of color pigment, a complicated preparation process and the like have remained.
The main object of the present invention is to provide an aluminium pigment colored to a high chroma by depositing a color pigment on the surface of the aluminium pigment, thereby allowing to improve the defect in chroma inherent in conventional aluminium pigments.
Another object of the present invention is to solve the problems on the coloring of conventional aluminium pigments such as color fading, defect in chroma, complication of preparation process and the like and as a consequent, to provide colored aluminium pigments suitable for use in paints or inks or molded resins.
In order to achieve the objects set forth above, a color pigment must adhere to at least the whole surface of individual particle of aluminium pigment. If there are some particles of aluminium pigment remained uncoated with color pigment, the light directly reflected by these uncoated particles will damage the brightness of color tone. When such colored aluminium pigments are used to prepare paints or inks or molded resins as well, the exfoliation of color pigment may happen in the course of the preparation processes and consequently, the resultant aluminium pigment having a surface uncoated with color pigment may damage the brightness of color tone.